Marfan syndrome is a congenital disease in which fibrillin biosynthesis is abnormal. Gradual aortic root dilation and subsequent rupture is the pathologic process responsible for early demise in patients with this disease. b-adrenergic receptor antagonists are proven to delay this process, and are therefore the standard long term prophylactic treatment. These medications however have side effects that frequently impacts on the patients' compliance with their regimen. In this study we will prospectively assess the efficacy of long acting verapamil for the delay of aortic dilation in patients with Marfan syndrome. Patients that are intolerant to or unwilling to comply with b-adrenergic receptor antagonists will be offered randomization to treatment with long acting verapamil versus placebo. Serial echocardiographic evaluation will be performed. The duration of the study is two years, with 1 year interim safety monitoring. The following parameters will be measured in all patients: Heart rate, blood pressure, aortic diameter, cross sectional area and aortic ratio, ejection force, aortic stiffness, distensibility and pulse wave velocity. The efficacy of treatment with verapamil will be evaluated by comparing this group with the b-blocker and no treatment groups.